Databases are expected to provide durable storage of data, resilient against system and power failures. The standard mechanism used to enable recovery from such failures is to create a journal or log of updates made to the database from some known initial or checkpoint state. Before any change to the database is committed or processed, a log record indicating this change must be written out to disk or other non-volatile memory. At recovery time, the log records can be traversed to recapture the effects of all committed updates.
Disk I/O is typically the biggest bottleneck in database performance, and the writing of log records accounts for a significant fraction of the disk I/O in most database systems. In main-memory database systems in particular, log writes may account for nearly all of the disk I/O activity. A reduction in the amount of log information that needs to be recorded will boost overall performance.